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  • 1
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Für das Problem einer durch einen dielektrischen Stab in einem rechteckigen Wellenleiter verursachten Diskontinuität wird eine exakte Feldlösung angegeben. Der Wellenleiter wird dabei in drei Bereiche eingeteilt, in denen das Feld in Form von Zylinderwellen oder Wellenleitermoden ausgedrückt wird. — Durch punktförmige Anpassung wird ein System linearer Gleichungen gefunden, aus dem sich Reflexions- und Transmissionskoeffizienten bestimmen lassen. — Als Anwendungsbeispiel wird eine Flüssigkeitssäule in einem zylindrischen Glasrohr untersucht. Für diesen Fall werden Diagramme angegeben, aus denen die Beziehungen zwischen den Transmissions- und Reflexionsfaktoren zu den dielektrischen Konstanten der Probe entnommen werden können. — Solche Kurven werden zur Messung der dielektrischen Eigenschaften von Flüssigkeiten benutzt.
    Notes: Contents An exact solution of the discontinuity problem of a circular cylindrical dielectric post centered in a rectangular waveguide is presented. The waveguide is divided in three regions where the field is expressed in cylindrical waves or in waveguide modes. By point matching, a system of linear equations determining the reflection and transmission coefficients is found. — The structure of our interest includes a liquid column surrounded by a cylindrical glass tube. For this case, curves have been made showing the relationship between the coefficients of reflection and transmission and the permittivity of the rod. Such curves are used for measuring the dielectric properties of liquids.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 66 (1983), S. 117-124 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht In dieser Arbeit wird die exakte Lösung für das elektromagnetische Feld, das durch einen perfekt leitenden elliptischen Kegel gebeugt wird, angegeben. Die Lösung wird in der Gestalt der dualen Greenschen Funktion dargestellt, welche die allgemeine Form der Lösung ist. Es wird das sphärisch-konisches Koordinatensystem gebraucht, wobei der elliptische Kegel eine Koordinatenfläche ist. Es werden Ergebnisse für die ersten am meisten beitragenden Eigenwerte und Eigenfunktionen, als auch für das Feld der entfernten Zone, angegeben.
    Notes: Contents In this paper, the exact solution for the electromagnetic field diffracted by a perfectly conducting elliptic cone is determined. The solution is presented in the form of a dyadic Green's function which is the most general form of solution. It is used the spheroconal coordinate system where the elliptic cone is one of the coordinate surfaces. Results will be shown for the first main contributed eigenvalues and eigenfunctions and for the far zone field in some special cases.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 70 (1987), S. 195-203 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Das Problem der Diskontinuität eines dielektrisch ummantelten Metallstiftes in einem Hohlleiter ist numerisch gelöst worden. Parameterkurven sind aus der Lösung abgeleitet worden und stellen die Parameter des T-äquivalenten Stromkreises in Abhängigkeit von der Geometrie des Stiftes dar, wobei unterschiedliche Permeabilitäten des dielektrischen Mantels berücksichtigt wurden. Für bestimmte Verhältnisse zwischen der Frequenz, der Dielektrizitätskonstanten und des Stiftradius wird der Reflektions- oder der Transmissionskoeffizient gleich Null. Diese Verhältnisse ergeben NB-Filter. Versuchsergebnisse haben die Nützlichkeit der Methode als Verfahren für den Filterentwurf gezeigt.
    Notes: Contents The discontinuity problem of a metallic post coated by a dielectric tube in a rectangular waveguide has been solved numerically.—From the solution parametric curves have been derived displaying the parameters of the T-equivalent circuit in dependence of the post geometrie. Several cases of the dielectric tube permittivity are considered. For some special relations between the frequency, the dielectric constant and the radius of the post the reflection or the transmission coefficient becomes equal to zero. These relations give narrow-band filters. Experimental results have shown the utility of the method as a filter design tool.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 78 (1995), S. 271-280 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Es wird eine einheitliche Formulierung für Supergain-Längsstrahler mit Tschebyscheff- und Legendre-Polynomen vorgestellt. Die Strahlergruppen werden für unterschiedliche Kombinationen dieser Polynome angegeben, ebenso ihre optimalen Richtgewinne wie auch der dazugehörige Strahlungs- Wirkungsgrad in der Hauptrichtung und der GütefaktorQ. Einige Beispiele belegen die Einfachheit der Formulierung.
    Notes: Contents A unified formulation for superdirective end-fire arrays by using Chebyshev and Legendre Polynomials and their maximum directivities as well as the corresponding efficiency index and theQ factor are found. Several examples show the simplicity of the formulation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 9 (1999), S. 250-255 
    ISSN: 1432-1084
    Keywords: Key words: CT ; Abdominal trauma ; Unstable hemodynamic condition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. This article is an appraisal of the use of CT in the management of patients with unstable abdominal trauma. We examined 41 patients with abdominal trauma using noncontrast dynamic CT. In 17 patients a postcontrast dynamic CT was also carried out. On CT, 25 patients had hemoperitoneum. Thirteen patients had splenic, 12 hepatic, 6 pancreatic, 8 bowel and mesenteric, 12 renal and 2 vascular injuries. Seven patients had retroperitoneal and 2 patients adrenal hematomas. All but five lesions (three renal, one pancreatic, and one splenic) were hypodense when CT was performed earlier than 8 h following the injury. Postcontrast studies (n = 17), revealed 4 splenic, 3 hepatic, 1 pancreatic, 3 renal, and 2 bowel and mesenteric injuries beyond what was found on noncontrast CT. Surgical confirmation (n = 21) was obtained in 81.81 % of splenic, 66.66 % of hepatic, 83.33 % of pancreatic, 100 % of renal, 100 % of retroperitoneal, and 85.71 % of bowel and mesenteric injuries. The majority of false diagnoses was obtained with noncontrast studies. Computed tomography is a remarkable method for evaluation and management of patients with hemodynamically unstable abdominal trauma, but only if it is revealed in the emergency room. Contrast injection, when it could be done, revealed lesions that were not suspected on initial plain scans.
    Type of Medium: Electronic Resource
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